CRASH AND BURN ARIANE 5 Kristen Hieronymus SYSM

CRASH AND BURN ARIANE 5 Kristen Hieronymus SYSM 6309 Advanced Requirements Engineering 20130622

TABLE OF CONTENTS The Rocket The Payload 37 Seconds After Launch Video Root Cause Analysis Result Irony Continuing Spin Story

ARIANE 5 ROCKET June 4, 1996 launch European Space Agency rocket $7 Billion development cost 10 years development time

PAYLOAD “Cluster” payload European Space Agency program, in cooperation with NASA 4 satellites on-board To fly in tetrahedral formation To study Earth’s magnetosphere

37 SECONDS AFTER LAUNCH… Rocket self-destructed

VIDEO http: //en. wikipedia. org/wiki/Ariane_5 http: //upload. wikimedia. org/wikipedia/commons/8/81/Ariane_5_10 _2007. ogg

ROOT CAUSE ANALYSIS Trying to put a 64 -bit value in a 16 -bit register caused an overflow condition, which led to…

ROOT CAUSE ANALYSIS 2 The guidance system shut down, which led to…

ROOT CAUSE ANALYSIS 3 The backup (identical) guidance system shutting down after encountering the same error, which led to…

ROOT CAUSE ANALYSIS An error message to the steering system, which the steering system interpreted as numbers from the guidance system, rather than a textual message, which led to…

ROOT CAUSE ANAYSIS The steering system made an unnecessary and abrupt course correction, which led to…

ROOT CAUSE ANALYSIS Aerodynamic forces ripped off the boosters from the rocket, which led to…

ROOT CAUSE ANALYSIS Complete disintegration of the rocket, which led to…

RESULT Complete loss of the rocket and the four expensive, and uninsured satellites onboard

IRONY The system which produced the overflow was not needed on the Ariane 5! Leftover from Ariane 4, due to reuse of entire subsystem (cost savings) Different preparation sequence from Ariane 4 Velocity on Ariane 5 higher than Ariane 4

MORE IRONY Ariane 4 had requirement to not use more than 80% of memory So, 4 variables had error protection code, but 3 others didn’t Velocity variable was one which didn’t have protection code

ON-GOING SPIN STORY Wikipedia lists as a “test launch” Test launches do not carry expensive payloads

LINKS http: //www. around. com/ariane. html http: //en. wikipedia. org/wiki/Ariane_5 http: //en. wikipedia. org/wiki/Cluster_mission